Dry-cargo marine containers come in many sizes, e.g., 20, 40, 45, 53 feet in length, typically rectangular or box-like, designed to be stacked one upon another according to ISO 1161 standard, for example. More specifically, ISO class containers come in following sizes: 20' (length).times.8' (width).times.8'6" (height); 40'.times.8'.times.8'6"; and 40'.times.8'.times.9'6" (Hi cube). Domestic class containers come in following sizes: 45'.times.8'6".times.9'6" and 53'.times.8'6".times.9'6". Referring to FIG. 1, a conventional container 10 of this type has a base assembly 12, four vertical corner posts 16 extending vertically from four lower corner fittings 14, two upper side and two upper cross beams 18 connected together to the four corner posts 16 via four upper corner fittings 20. The corner posts 16 extend between each pair of container's four upper and lower corner fittings 20, 14. The base assembly includes a floor panel (not shown) supported between a pair of lower side beams 18' and a pair of lower of cross beams 18. These beams and posts are typically made of bent sheet metal angles and channels.
The container(s) stacked above are designed to sit on the top four corner fittings 20 so that it, with the respective four corner posts 16, transmits weight to the bottom four corner fittings of the base assembly and to any internal frame at the front and rear sides.
The container of this type further includes a roof panel 22, two longitudinal side panels 24, a front assembly and a door assembly, and the floor. The side panels 24 generally support the roof and any objects resting or accumulated thereon, such as snow or ice. The container(s) stacked above is not designed to exert downward load on the roof or the four side panels. Thus, the side panels are not under compression from top to bottom. They, however, do act as diagonal braces to the frame since the side panels are welded to the side and cross beams 18, 18', and the corner posts 16 at their four edges.
Typically, each of the panels 22, 24 is formed from a plurality of corrugated sheets of commercial quality steel joined side-by-side by welding so that the joined seams run generally perpendicularly to the length of the panel. See FIG. 2. FIG. 1 shows the corrugation 30 more clearly. The corrugation, which is necessary to add strength or rigidity to the panel, are typically formed by a brake press.
Referring to FIG. 2, a plurality of corrugated steel sheets are butt welded side-by-side using traditional wire fill arc-welding techniques. This welding is slow and difficult to automate. Further, the arc-welding technique and the butt welding construction require a thicker panel than would be normally required for other types of welding.
Each side panel is welded to the horizontally extending side beams 18, 18' at their upper and lower corrugated edges. Specifically, during the following framing operation, the side panels are hung vertically while the undulating bottom edge is welded to the lower side beams 18' using conventional arc welding techniques. See FIG. 10C. This welding is slow and difficult to automate because of the undulating nature and lack of dimensional uniformity of the corrugation, and the poor fit-up to the base assembly 12. Moreover, the manufacturing tolerance variations generated with the conventional cargo container designs and manufacturing processes make the automatic welding and assembly even more difficult. Further, because the panel has to be arc-welded or has butt welding construction or both, the panel has to be thicker than necessary, wasting material.
There is a need to automate cargo container assembly without the aforementioned drawbacks. The present invention meets this need.